at this point you take it to court. if you've used a good PFD letter and they agreed to it, this means you've A. specifically said you have NOT admitted responsibility for the charges and B. you are doing this in an attempt to get your record cleaned up in an expedient fashion.
those actions would never hold up - it doesn't matter if they were right in reporting the charge-off or whatever in the first place. even if they could prove you had an unpaid charge-off that was previously yours, that doesn't undo their more recent action of agreeing to remove the charge-off (implicit in this agreement is the facts that the charge might not have been yours, as asserted in your PFD letter - if they disagreed with what you asserted there, they shouldn't have agreed to the contract you put forth).
the previous disagreement of the facts doesn't undo their most recent action.
